Which property needs to be set for script manager control to extend the time before throwing time out expection if no response is received from the server?

Answer:

AsyncPostBackTimeout Property needs to set which gets or sets a value that indicates the time, in seconds, before asynchronous postback time out if no response is received from the server.

 <asp:scriptmanager id="scriptManager1" runat="server" asyncpostbackerrormessage="We can not serve your request at this moment.Please try later." asyncpostbacktimeout="36000"></asp:scriptmanager>

The default value of this property is 90 second. We can also set the user defined error message using asyncpostbackerrormessage property (as shown in above code) for time out.